I wouldn't consider a mixer being the 'fastest' as a useful metric since you purposely want to add some form of a (multi hour) delay between depositing and withdrawing the coins.

In terms of large amounts (in my case >0.5BTC), I wouldn't feel comfortably using anything but ChipMixer. I'm confident that most established mixers will do their work relatively well with amounts below 0.10BTC, but above that things will start to get complicated liquidity wise, and I rather avoid such situations by using a proven high liquidity mixer.